Manufacture of impregnated articles



Patented Mar. 26, 1935 I UNITED STATES PATENT OFFICE MANUFACTURE OF IDH'REGNATED ARTICLES George A. Richter, Berlin, N. H., assignor to Brown Company, Berlin, N. H., a corporation of'Maine a No Drawing. Application January 20, 1932, Serial No. 587,790

8 Claims. (01. 91-70) There are classes of articles or products which chains. Nekal A is the crude sodium salt of octo-' are impregnated through the use of impregnants hydro-anthracene metasulphonic acid, while Incontained in an aqueous vehicle, the water servdrapid and Nekal S are similar but contain the ing as the solvent or suspending medium for the free acid. Nekal AEM is a combination of Nekal impregnant and further for carrying the impreg- A with methylhexalin. Neomerpin N is a high 5 nant into and through the articles or product. molecular weight sulphonic acid. Some of these In such cases, the impregnant is usually either wetting-out agents can be readily decomposed by dissolved in. the aqueous medium or is held in heat or by the use of suitable acids or alkalies, colloidal suspension therein so as to be capable of but, these treatments should not be practised in entering into articles or products whose foundawhen the heat, acid, or alkalies necessary for such 10 tion or base is more or less porous. The present destruction also injures the impregnant. For ininvention relates to this class of impregnation stance, an acid treatment should not be practised and the impregnated articles or products realized when the impregnant is rosin soap or other acid- 1 therefrom. decomposible body. On the other hand, an acid In accordance with the present invention, I treatment in which the acid is, for instance, disl5 carry out such impregnation in the presence of solved inwater or exists as a vapor or gas phase, so-called wetting-out agents, which may be apmight be relied upon when inert waterproofing plied to the base being impregnated either be ingredients like asphalt, paraflin, or the like have fore or together with the aqueous vehicle conbeen used in the form of aqueous dispersions as taining the inipregnant. After such impregnathe impregnating media. All of the wetting-out 20 tion has been effected, I then destroy the wetagents can be removed, however, from the im- 1 ting-out agent in the sense that the agent is either pregnated foundation by leaching out with water, removed or chemically decomposed subsantially wherefore, after the impregnated foundation has in nti y and he no longer functions in t e been dried to fix the waterproofing ingredients impregnated article or product. While not limtherein in a water-insoluble state, the dried, im 25 ited thereto, my invention is especially useful in pregnated foundation can be steeped in a water the treatment of fibrous foundations when it is bath until the wetting-out agent has been subdesired to impregnate them with aqueous im- .Vstantially completely extracted, and then redried. pregnants imparting such qualities as water re- The water bath may be heated, ifdesired, to propellency thereto. The presence of wetting-out mote the extraction of the wetting-out agent from 30 agents during impregnation phenomenally inthe impregnated foundation. creases the rate at which water penetrates into a The principles of the present invention may be 'fibrous foundation, and thus promotes a uniform applied to advantage, for example, in producing impregnation of the foundation with the impregan effectively sized paper, especially when the nant contained in the aqueous medium. When starting paper base is not especially porous and 35 the impregnated product is dried, however, it is it is to undergo impregnation with aqueous imnot possessed of the desired water repellency bepregnants of a colloidal nature, like rubber latex, cause of the presence therein of the wetting-out aqueous glue or rosin size solutions, and aqueous agent, which accelerates the penetration'of water dispersions of asphalts, waxes, resins, or the like, 40 into the prod ct even though a Waterproofing which do not penetrate the base with facility. In 0 V agentis associated with the product throughout. 'such case, I "incorporate Nekal BX, for example, BY destroying the Wetting-out agent afte it has into the paper. This incorporation can take performed its function, as my invention requires, place before the paper is dipped into the bath of it is possible to arrive. ata product having the aqueous sizing medium. On the other hand, the desired water-repellent quality. Nekal BX can be added directly tothe bath so 45 There are various wetting-out agents which are as to enter into the paper simultaneously with commercially available for use in accordance with the size. In either event, the wetting-out agent, my invention, for instance the wetting-out agents even when used in exceedingly small amount, sold under the trade names Nekal A, Nekal vastly enhances the p ed and u i y f AEM," Indrapid, Nekal S, Nekal BX, Neopenetration .of the size into and through the 50 merpin, Neomerpin N, all of which are either pape F p as little as, S y. f10m 5% benzene, naphthalene, or anthracene derivatives .to0.25% of Nekal BX added to a sizin t L having side chains. Thus, Nekal BX, which is a works an astonishing increase in penetrability of highly effective wetting-out agent, is the sodium the size into and through the paper. The sized salt of a naphthalene sulphonic acid with side paper is then dried and the Nekal BX deposited 55 therein may be destroyed by suitable heat or acid treatment, or by extraction with water, the particular mode of destruction depending on the specific sizing agent used. When gelatin or glue is used as a size, a suitable tanning or insolubilizing agent, e. g., alum, for such size may be added with the size or subsequent to the addition of the size for the purpose of inhibiting undesirable action upon size of water or aqueous chemical solutions subsequently employed for extracting the wetting-out agent. The resulting sized paper possesses a surface which can be satisfactorily written or printed upon with the usual kinds of printing or writing inks made up with water as the ink vehicle. Had the Nekal BX been permitted to remain in the paper, the printing or writing with such inks on the paper would have been attended by a highly objectionable spreading of the ink and the formation of feathered or blurred imprints.

There are instances when a. paper or other foundation has already undergone impregnation with waterproofing ingredients like those already mentioned and so is difiicultly, if at all, penetrable even by aqueous solutions of compounds which may be desirable secondary impregnants. For example, a web of interfelted fiber may have been bituminized, as by dipping into molten asphalt, to produce a dense, impregnated sheet highly resistant to penetration by water on account of the fibers being enveloped by a continuous bitumen phase amounting by weight to much more than even the fibers. Yet it might be desirable to incorporate into the bituminized sheet agents'from an aqueous vehicle, for instance, agents like the phosphates and tungstates, which are water-soluble and which impart fire resistance to the sheet. The property of fire resistance is, of course, desirable when the bituminized sheet is to be used as a building material, e. g., on a roof. I have found that in this connection the use of Nekal BX or equivalent wetting-out agent in amount of, say, 0.1% to 0.2% in the aqueous vehicle containing a fire retardant or other secondary impregnant is most advantageous, as it makes possible the desired secondary impregnation. A bituminized sheet which has thus been impregnated with phosphates or tungstates as the fire retardants contain these retardants where they are most effective in their action, namely, on the bitumen phase, which is the phase first exposed to the fire. The bitumen phase contributes to the fire hazard properties even more than the fiber foundation, especially when present in amount much more .than the fiber, as is usually the case in bituminized webs for roofing or other building purposes. Moreover, it is easy to diminish the combustibility of the fibrous base by making it partly or entirely of incombustible fiber, such as asbestos, or if made of combustible fiber such as cellulose, by treating such fiber with fire retardants of the type mentioned. The destruction of the wetting-out agent after the drying of the bituminized sheet containing fire retardants as the secondary impregnants, as by heating, is of course most desirable, since otherwise the wetting-out agent would promote the imbibition of water by the sheet, and would thus depreciate the value of the sheet for roofing or other purposes where water resistance is required. Moreover, the presence of a wetting-out agent in the sheet would conduce to a leaching out by water of water-soluble fire retardants incorporated into the sheet.

In those cases where a foundation of cellulose fibers is impregnated in the presence of a wetting-out agent with rubber latex and/or aqueous dispersions or emulsions of asphalt, parafiin, or other bodies which are practically inert with respect to strong solutions of alkali, the wetting-out agent may be destroyed, after the impregnated foundation has been dried, by strong solutions of alkali, for instance, solutions of caustic soda of about 10% to 18% or higher concentration. The treatment with such caustic soda solutions can be carried out at room temperature and be followed by the use of wash water to remove the alkali.

The foundation material being treated in ac- I cordance with the present invention need not necessarily be fibrous, although, so far as I am now aware, the greatest utility of my invention resides in the treatment of fibers of vegetable, mineral, or animal origin, in bulk condition or in the form of fibers integrated either on textile machines as bats, felts, or woven fabrics, or on machines of the papermaking class as webs or papers of interfelted texture.

I claim:

1. A process which comprises impregnating a base in the presence of a wetting-out agent with an aqueous medium containing a dispersed waterproofing agent for said base, drying the impregnated base, and destroying the wetting-out agent in said impregnated base.

2. A process which comprises impregnating a fibrous sheet in the presence of a wetting-out agent with an aqueous medium containing a water-repellent size for said sheet, drying the sized sheet, and destroying the wetting-out agent in said sheet.

3. A process which comprises impregnating a fibrous sheet carrying a water-repellent impregnant in the presence of a wetting-out agent with an aqueous medium containing a second impregnant for said sheet, drying the sheet containing both impregnants, and destroying the wettingout agent in said sheet.

4. A process which comprises impregnating a bituminized fibrous sheet in the presence of a wetting-out agent with an aqueous solution of a fire retardant, drying the impregnated sheet, and destroying the wetting-out agent in said sheet.

5. A process which comprises impregnating a bituminized fibrous sheet in the presence of the wetting-out agent with an aqueous solution of a fire retardant and drying the impregnated sheet.

6. A process which comprises impregnating a base in the presence of a wetting-out agent with an aqueous medium containing a dispersed, thermoplastic waterproofing agent for said base, drying the impregnated base, immersing the dried base in water to leach out the wetting-out agent therefrom, and re-drying the base.

'7. A process which comprises impregnating a bituminized fibrous sheet with an aqueous solution of a fire retardant in the presence of a wetting-out agent destructible by heat, drying the impregnated sheet, and heating it to destroy said wetting-out agent.

8. A process which comprises impregnating a bituminized fibrous base made up at least in part of asbestos fiber with an aqueous solution of a fire retardant in the presence of a wetting-out agent destructible by heat, crying the impregnated base, and heating it to destroy said wetting- Out agent.

' GEORGE A. RICHTER. 

